1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method for the same. More particularly, the present invention relates to a semiconductor device containing a copper containing metal wiring line and a manufacturing method for the same
2. Description of the Related Art
In recent years, a low resistance material such as copper is used as a wiring line material for demand of the high speed operation of a semiconductor device.
As a damascene process for forming a copper wiring line structure, a single damascene method and a dual damascene method are known. In the single damascene method, only a wiring line is formed by the damascene process. In the dual damascene method, a wiring line groove is embedded with copper in addition to a connection hole, to form the connection plug and the wiring line. Conventionally, in the single damascene method, the connection plug is formed of a refractory metal such as tungsten. However, in the dual damascene method, the connection plug is formed of a copper containing metal in addition to the wiring line. Therefore, the low resistance of the wiring line structure can be realized, and it is possible to contribute for the high speed operation of the semiconductor device.
FIGS. 1A to 1E are cross section views showing the wiring line structure formed by a method forming of the connection plug and the wiring line by the dual damascene method. FIG. 1A is a cross sectional view showing a state in which a first copper containing metal wiring line 220a has been formed. First, processes to the state of FIG. 1A will be described. First, a first silicon nitride film 212 and a first silicon oxide film 214 are formed on a semiconductor substrate 210 on which devices such as a transistor are formed. Subsequently, a wiring line groove is formed in the first silicon nitride film 212 and the first silicon oxide film 214 by a dry etching. A barrier metal film 216a and a copper film 218a are formed in this order to fill the wiring line groove. Subsequently, the surface of the substrate is flattened by a CMP method. Thus, the first copper containing metal wiring line 220a is formed. Subsequently, a second silicon nitride film 222 and a second silicon oxide film 224 are formed. In this way, the state of FIG. 1A is achieved.
Next, as shown in FIG. 1B, a connection hole 226 for a connection plug and a wiring line groove 228 are formed in a second silicon oxide film 224 by a lithography method and an etching method. Subsequently, an etching gas is changed and the etching of a second silicon nitride film 222 is carried out. Subsequently, as shown in FIG. 1C, the barrier metal film 230 is formed on the whole of second silicon oxide film 224 having the connection hole 226 and the wiring line groove 228.
Next, as shown in FIG. 1D, a copper film 232 is formed on the barrier metal film 230 and fills the connection hole 226 and the wiring line groove 228.
Next, as shown in FIG. 1E, the surface of the substrate is flattened by the CMP method, and the copper film 232 and the barrier metal film 230 in a portion other than the wiring line groove 228 are removed. Thus, the connection plug 234 and a second copper containing metal wiring line 220b are formed.
By repeating a series of the above-mentioned processes, the semiconductor device is formed to contain a multiple wiring line structure.
However, as mentioned above, when a wiring line and a connection plug are formed of copper by the dual damascene method, a production yield of the semiconductor device is so low that the semiconductor device can not be produced stably.
Also, in order to use the semiconductor device stably for a long term, points to be improved are still remained. Therefore, further improvement is demanded to increase the reliability of the semiconductor device. It is easy for copper and copper containing metal to cause migration, and the migration is supposed as one of the estimated causes that such a problem occurs. However, the cause is not clear.